This is a little thing but....

Usually we have a shop standard for our viewport and so you can just select it from the drop down and so you know what your scale is.

BUT

sometimes when setting our Viewport Scale, we zoom to get the product big enough to see. The button in the ribbon will just read "Custom" (Same in the Properties Panel). So I'm not really sure how you know what the actual scale is. So then I'll click around in the drop down and try to match in the preset size what I see...But I would love for it to tell me the exact scale. 

(Is there already a way to find out?)